Regular spray guns include two types, one is high pressure type and the other is low pressure type, and both are designed for respectively specific purpose. The high pressure type spray gun directly sucks up the paint from the bottle to the nozzle by means of siphon without permitting high pressure air to enter into the bottle. This high pressure spray gun can provide a fine spraying effect and is most practical for spray painting on cars and furnitures. However, since the high pressure spray gun sucks the liquid material by means of siphon, high concentration paint is be not applicable for use therein and should be diluted to a proper range. The additional process of diluting the painting prolongs the operation and consumes extra diluent. The low pressure type spray gun permits compressed air pressure run to enter into the bottle to help delivery of the paint and is practical for spraying high concentration paint by minimizing operational time and reducing material consumption. However, in order to prevent explosion of the bottle, the pressure applied for low pressure spray gun must be constantly controlled within a low level, such that the pressure at the nozzle may become excessive low and the spraying effect may not be effectively performed. Therefore, the low pressure spray gun is not practical for high quality operation. When using a high pressure spray gun, if air pressure is below 100 psi, the siphon effect will be unable to perform. Therefore, minimum air pressure of over 100 psi is required for operating a high pressure spray gun. When using a low pressure spray gun, if air pressure exceeds 50 psi, the spray bottle cover may break away from the bottle or the bottle may explode. Therefore, air pressure within 50-100 psi is not applicable for use in low pressure spray gun.
In view of said problems, a safety exhaust valve equipped spray gun of the present invention was created for providing a spray gun which is applicable for concomitantly high pressure as well as low pressure operation.
The main object of the present invention is to provide a safety exhaust valve equipped spray gun wherein the spray gun and spray bottle cover are incorporated into one unit with a safety valve provided on the spray bottle cover above the connecting portion, so as to permit a spring leaf to drive a lever to force a steel ball to block the air hole, thereby preventing air leakage at time the limited air pressure range it fixed below 50 psi; or to permit excessive high air pressure which is over 50 psi to push open the steel ball to permit excessive air pressure to be exhausted through an exhaust hole and to permit the inner air pressure to be constantly maintained within 50 psi. Thus, the present invention provides a spray gun with maximum spraying performance, preventing the spray bottle from breaking away from the spray gun or from exploding.
Another object of the present invention is to provide a safety exhaust valve equipped spray gun wherein the air pressure in the spray bottle is constantly maintained within a limited range. The air pressure in the bottle is used to force the liquid material to spray through the nozzle. An air pressure stabilizing is provided at the front of an air induction hole to maintain a constant air pressure for the air induction hole and the nozzle, so as to provide a maximum spraying effect and to provide higher pressure for enhancing performance, and also to provide a practical spray gun for high pressure as well as low pressure spraying operation.
A yet further object of the present invention is to provide a safety exhaust valve equipped spray gun, wherein a bolt is threaded in the bottom of the inner air induction hole. The bolt is arranged to provide a stepped hole with the bottom of the hole having a check spring attached thereto for permitting air to smoothly run into the spray bottle, thereby providing stability. This arrangement also prevents liquid material from running into the air induction hole when the spray bottle is turned upside-down.
The above and other objects, features and advantages of the present invention will be fully understood from the following description considered in connection with the accompanying drawings which illustrate the best mode for practicing this invention.